1. Field of the Invention
The present invention relates to plate-like polycrystalline particles, methods for producing plate-like polycrystalline particles, and methods for producing crystallographically-oriented ceramics.
2. Description of the Related Art
To date, crystallographically-oriented ceramics whose piezoelectric properties are improved by increasing the degree of orientation of a specific crystal plane contained in the crystals have been proposed (for example, refer to Japanese Unexamined Patent Application Publication Nos. 11-60333 and 2003-12373). Furthermore, as the method for producing a crystallographically-oriented ceramic, a method has been proposed which includes a mixing step of mixing a host material A which has shape anisotropy and a guest material B which has crystal coherency with at least one crystal plane of the host material A and low crystal anisotropy, an orienting step of orienting a crystal plane of the host material A, and a firing step of heating the mixture to orient a crystal plane of the guest material B, and in which it is possible to obtain a ceramic with increased orientation even if the guest material B having low crystal anisotropy is used (for example, refer to Japanese Unexamined Patent Application Publication Nos. 2003-12373 and 10-330184). Furthermore, a method in which the orientation of a host material itself is increased by hydrothermal synthesis has been proposed (for example, refer to Japanese Unexamined Patent Application Publication No. 2007-22857).